Biological Treatment of Microbial Corrosion

Opportunities and Challenges

Reza Javaherdashti, Kiana Alasvand

• Publisher: Elsevier
• Year: 2019
• Print ISBN: 9780128161081
• eBook ISBN: 9780128162996
• Topic: Tecnología e ingeniería
• Subtopic: Ciencias de los materiales

Biological Treatment of Microbial Corrosion: Opportunities and Challenges explores the latest biological approaches to microbial corrosion and its inhibition. The book provides comprehensive information on the current knowledge of microbes involved in corrosion and their mechanisms of action on corrosion induction and inhibition. This information is helpful for a wide range of audiences, from university researchers, to industry specialists. The book discusses foundational information about corrosion and microbiologically influenced corrosion and its importance. Other chapters provide an in-depth review of corrosion causing microorganisms, their properties and their mechanism of involvement in MIC.Updated findings on the biological treatment of corrosion are addressed, as are future opportunities and challenges that could lead to prosperous, sustainable and secure industrial application of these techniques.- Provides a detailed overview of the fundamental concepts of corrosion- Discusses MIC, including its characteristics, properties and modelling- Previews the opportunities and challenges faced by the utilization of biological treatments for corrosion

Chapter 1

Why Corrosion and Particularly Microbial Corrosion Are Important?

The Definition of Engineering Importance as a Function of “Risk” and “Cost”

Anything can be specified with two variables: its importance (the role that it plays in our lives) and the cost of being at this status. A rather trivial example could be our pets: the role that these lovely creatures may play in the lives of many of us is hard to deny. On the other hand, the cost for looking after them is a figure that many won't (can't) afford. Of course here we don't mean economy for keeping a pet, I am sure many of us have experienced the rather bitter feeling when we have read “No Dogs Allowed” signs or even the trauma that may be felt when a loved pet is not with us anymore. All these can make something, from a pet to corrosion, become important for us.

However, the importance of anything is rather a relative measure: something that may be important for someone may not be important for another person. Engineering importance, on the other hand, is another story. In fact, engineering importance because of its very nature cannot vary from person to person. It has a clear, mathematical definition that can be stated as below:

EngineeringImportance=Cost×Risk

Each of these terms has its own nonvarying, definitive meaning as we shall explain below in a moment. However, we have to add a very significant point here too: if engineering importance of something is important, no excuse is acceptable for ignoring it. Although this statement may sound obvious, our real life experience shows that in many cases in industries, the engineering importance of corrosion is taken not with the gravity it deserves.

When it comes to corrosion, we, as H.H. Uhlig did, can categorize corrosion losses as below:

• 1. Waste of energy and materials
• 2. Economical loss
• • a. Direct loss
  • b. Indirect loss
  • • i. Shutdown
    • ii. Loss of efficiency
    • iii. Product contamination
    • iv. Overdesign

We will very briefly just touch economic-ecologic aspects of corrosion loss. However, this is not to be understood that other aspects of corrosion loss can be ignored. Take, for example, the overdesign that will be imposed to compensate for corrosion.

Assume that we have a 32-inch pipeline with a length of 10 km. If the thickness of the pipe is 5 mm, the internal volume of the pipe will be 5064.0 m³. However, if we could manage to decrease this overdesign to 3 mm, the internal volume will be increased to 5114.0 m³, in other words the internal volume will be increased by more than 90%.

The above shows that the overdesigning to be protected against corrosion is not an engineering solution. In addition to decreasing the useful volume of the pipe, overdesigning can indirectly add up more into the pollution: overdesign as a measure of protection against corrosion will add into the “embedded energy” (EmE). Embedded energy is defined as “the energy consumed by all of the processes associated with the production of a structure from the acquisition of natural resources to product delivery.”² Therefore, when we do overdesign, we are augmenting the energy required to make the part (in our example, the 10-km, 32-inch pipe). This augmented energy will consume up more energy from extraction and refining of the metal to melting and shaping and deformation. Just multiply this figure by the total length of pipelines used around the world and those that are designed not to pose any corrosion risk by applying overdesign.

The example above can be taken as a stand-alone case of how corrosion can affect our lives and energy sources. Below, we will briefly introduce some economic-ecologic disadvantages of corrosion.

What are the Risks and Costs of Corrosion and Microbial Corrosion

We will start with what we mean by “cost” in the definition of engineering importance. In the context of this chapter, cost will mean anything that will increase the likelihood of creating a hazard to our investment. When we build a power plant or a refinery, for example, we do it by considering if this investment is feasible enough for us. In other words, we study the items required to ensure us that we are not “wasting our money.” One important parameter here is the cost that is imposed on our investment—that is, the power plant or refinery or pipeline grid we make. The cost here can be categorized into two sets: the intrinsic costs associated with the pass of time and effect of elements on our investment (that can roughly be addressed as “depreciation” factor) and the costs that our investment may impose on the surrounding environment (ecologic costs). We will describe the depreciation under “economic costs,” bearing in mind that depreciation in its very financial meaning does not include corrosion properly, as we will discuss it below.

Economical Costs

Whenever we do an investment, we are also obliged to think how long this investment will last. Especially if the investment is in a physical form (for instance, building up a power plant, a refinery, or the like), we are also interested to know how long we can expect this investment will last as well as after what period in time, this investment will start to become economically feasible. All physical assets we have in industry are exposed to the elements and thus will go through a process known by economists as “erosion”: the value of your initial investment will depreciate by many factors such as “wear and tear.” If we can assume a certain rate of annual depreciation/wear and tear for a physical asset, then it will be possible to also calculate from what point in time the asset will start to become economically feasible (this point in time is the “break-even point”).

However, there are at least two shortcomings in such economical considerations:

• 1. Wear and tear—as the name also implies—can only contain physical forms of corrosion such as but not limited to erosion-corrosion or perhaps rusting (in iron and steel alloys). The term is not inclusive of chemical, electrochemical, and biologic factors that can affect corrosion and bring it to the final stage of having lost its mechanical integrity and strength.
• 2. Although the depreciation rate may be assumed certain, constant value for each year, as it is not considering the wider concept of corrosion, the actual depreciation rates to be imposed on the material will be much higher than what is expected on the paper. The main reason behind intensifying deprecation rates is corrosion.

Having said the above, it is now evident that as long as there is no mutual understanding between corrosion experts and economists, what is being reported as “cost of corrosion” must be taken as the very minimum values that could have been surveyed and cal...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1. Why Corrosion and Particularly Microbial Corrosion Are Important?
• Chapter 2. A Brief Introduction to Corrosion Engineering
• Chapter 3. An Introduction to Microbial Corrosion
• Chapter 4. An Introduction to Microbiology for Nonmicrobiologists
• Chapter 5. Biologic Treatment of Corrosion
• Chapter 6. Future Perspective of Biological Inhibition of Corrosion
• Index